For decades Electroencephalography (EEG) and related tools that measure psychophysiological responses (e.g., polygraphs) have been used to discern whether someone is familiar with certain information. Examples of EEG tools include the systems and methods disclosed in U.S. Pat. No. 8,684,926 B2 and U.S. Patent Application publication 20140163409 A1 (each of which is incorporated by reference in its entirety). Systems such as these, are generally used in conjunction with the Guilty Knowledge Test (GKT). The purpose of the GKT is to associate the test subject to a particular event (e.g., a crime) by observation and interpretation of the test subject's psychophysiologic response when confronted with information that could only be known by someone familiar with the event.
Success of the GKT requires that the investigator know about the people, places or things associated with an event in order to pose verbal or non-verbal questions to the test subject. The investigator compares the test subject's psychophysiologic response to questions known to be related to the event with questions known to be unrelated to the event. The reliability of test results depends upon the test administrator's knowledge of what the test subject knows or is believed to know and subjective interpretation of observed psychophysiologic response of the test subject. There is a need for a non-verbal means of deducing what a person is familiar with by objective interpretation of psychophysiologic responses to that do not rely upon a priori knowledge of what the test subject knows.